A leading cardiologist yesterday raised doubts about the medical screening which Premier League footballers undergo after it failed to detect the problem which led to Fabrice Muamba's collapse on Saturday.

Doctors worked for two hours to get the Bolton Wanderers midfielder's heart beating again after he slumped to the ground a few minutes before half-time during the match against Tottenham Hotspur.

Sanjay Sharma, professor of cardiology at St George's Hospital, Tooting, south London, who runs Britain's only cardiac unit for sportsmen and -women and has screened 20,000 athletes, said: "I am surprised the heart problem was not picked up. The medical screening these players get is extremely comprehensive. It will identify 80 per cent of conditions causing sudden death."

Messages of support poured in for the Bolton Wanderers and former England Under-21 player, who remains "anaesthetised" and in a critical condition in hospital. Former teammate Gary Cahill wore a T-shirt with the words "Pray 4 Muamba" written across it, which he unveiled after scoring for his current club, Chelsea, yesterday.

Bolton's next scheduled opponents, Aston Villa, agreed to postpone their forthcoming match as a mark of respect. Sadly, the sympathy shown by the footballing community was not universal. A man was arrested yesterday on suspicion of racially abusing Muamba after a message was allegedly posted on Twitter and later deleted by a 21-year-old from Pontypridd.

"Our thoughts are with Fabrice's family and Bolton Wanderers and we are all willing him to pull through. Events such as this put everything into perspective," said Daniel Levy, chairman of Tottenham, Bolton's opponents in the FA Cup quarter-final tie.

The former Arsenal and Birmingham City player remains in a critical condition in intensive care in the Heart Attack Centre at the London Chest Hospital, where he was taken after collapsing in the 41st minute of the match. He received prolonged resuscitation at the ground and on the way to the hospital, where doctors got his heart working.

Bolton Wanderers manager Owen Coyle said: "Fabrice's family have asked me to pass on their thanks for the many, many kind messages of support from not only Bolton fans but also fans from clubs across the country and abroad."

The fast response of the medical team at Tottenham's White Hart Lane ground was praised by medical experts. Dr Graham Stuart, an FA-accredited cardiologist, said Muamba's chances of recovery were "significantly" aided by their speed in reaching him and beginning attempts at resuscitation.

"They were obviously very troubling scenes but the thing that was most vital was how quickly he received treatment," he said. "At that stage the support is critical and the speed of treatment is vital. Any delay can damage organs."